Document ctest_build() TARGET option

Source/CTest/cmCTestBuildCommand.h

@@ -60,10 +60,12 @@ public:
   virtual const char* GetFullDocumentation()
     {
     return
-      "  ctest_build([BUILD build_dir] [RETURN_VALUE res] [APPEND]\n"
-      "              [NUMBER_ERRORS val] [NUMBER_WARNINGS val])\n"
+      "  ctest_build([BUILD build_dir] [TARGET target] [RETURN_VALUE res]\n"
+      "              [APPEND][NUMBER_ERRORS val] [NUMBER_WARNINGS val])\n"
       "Builds the given build directory and stores results in Build.xml. "
-      "If no BUILD is given, the CTEST_BINARY_DIRECTORY variable is used. "
+      "If no BUILD is given, the CTEST_BINARY_DIRECTORY variable is used.\n"
+      "The TARGET variable can be used to specify a build target.  If none "
+      "is specified, the \"all\" target will be built.\n"
       "The RETURN_VALUE option specifies a variable in which to store the "
       "return value of the native build tool. "
       "The NUMBER_ERRORS and NUMBER_WARNINGS options specify variables in "